Modifying Reserved Instances

When your computing needs change, you can modify your Standard or Convertible Reserved
Instances and continue to benefit from the billing benefit. You can modify the
Availability Zone, scope, network platform, or instance size (within the same instance
type) of your Reserved Instance. To modify a Reserved Instance, you specify the Reserved
Instances that you want to modify, and you specify one or more target
configurations.

Note

You can also exchange a Convertible Reserved Instance for another Convertible Reserved
Instance with a different configuration, including
instance family. For more information, see Exchanging Convertible Reserved Instances.

You can modify all or a subset of your Reserved Instances. You can separate your original
Reserved Instances into two or more new Reserved Instances. For example, if you have
a
reservation for 10 instances in us-east-1a and decide to move 5 instances
to us-east-1b, the modification request results in two new reservations:
one for 5 instances in us-east-1a and the other for 5 instances in
us-east-1b.

You can also merge two or more Reserved Instances into a single
Reserved Instance. For example, if you have four t2.small Reserved Instances of one instance each, you can merge them to create one t2.large
Reserved Instance. For more information, see Modifying the Instance Size of Your
Reservations.

After modification, the benefit of the Reserved Instances is applied only to instances
that match the new parameters. For example, if you change the Availability Zone
of a
reservation, the capacity reservation and pricing benefits are automatically applied
to
instance usage in the new Availability Zone. Instances that no longer match the
new
parameters are charged at the On-Demand rate unless your account has other applicable
reservations.

If your modification request succeeds:

The modified reservation becomes effective immediately and the pricing benefit
is applied to the new instances beginning at the hour of the modification
request. For example, if you successfully modify your reservations at 9:15PM,
the pricing benefit transfers to your new instance at 9:00PM. (You can get the
effective date of the modified Reserved Instances by using the
DescribeReservedInstances API action or the describe-reserved-instances command (AWS CLI).

The original reservation is retired. Its end date is the start date of the new
reservation, and the end date of the new reservation is the same as the end date
of the original Reserved Instance. If you modify a three-year reservation that
had 16 months left in its term, the resulting modified reservation is a 16-month
reservation with the same end date as the original one.

The modified reservation lists a $0 fixed price and not the fixed price of the
original reservation.

Note

The fixed price of the modified reservation does not affect the discount pricing
tier calculations applied to your account, which are based on the fixed price
of the
original reservation.

If your modification request fails, your Reserved Instances maintain their original
configuration, and are immediately available for another modification request.

There is no fee for modification, and you do not receive any new bills or invoices.

You can modify your reservations as frequently as you like, but you cannot change
or
cancel a pending modification request after you submit it. After the modification
has
completed successfully, you can submit another modification request to roll back
any
changes you made, if needed.

Requirements and Restrictions for
Modification

Not all attributes of a Reserved Instance can be modified, and restrictions may
apply.

Modifiable attribute

Supported platforms

Limitations

Change Availability Zones within the same
Region

Linux and Windows

-

Change the scope from
Availability Zone to Region and vice versa

Linux and Windows

If you change the scope from Availability Zone to Region, you lose the capacity
reservation benefit.

If you change the scope from Region to Availability Zone, you lose Availability Zone
flexibility and instance size flexibility (if applicable). For
more information, see How Reserved Instances Are Applied.

The input Reserved Instances must be either Standard Reserved Instances or
Convertible Reserved Instances, but not a combination of both.

Modifying the Instance Size of Your
Reservations

If you have Amazon Linux reservations in an instance type with multiple sizes, you
can modify the
instance size of your Reserved Instances.

Note

Instances are grouped by family (based on storage, or CPU capacity); type
(designed for specific use cases); and size. For example, the c4
instance type is in the Compute optimized instance family and is available in
multiple sizes. While c3 instances are in the same family, you
can't modify c4 instances into c3 instances because
they have different hardware specifications. For more information, see Amazon EC2 Instance Types.

You cannot modify the instance size of the Reserved Instances for the following instance
types,
because only one size is available for each of these instance types.

cc2.8xlarge

cr1.8xlarge

hs1.8xlarge

i3.metal

t1.micro

Each Reserved Instance has an instance size footprint,
which is determined by the normalization factor of the instance type and the
number of instances in the reservation. When you modify a Reserved Instance,
the
footprint of the target configuration must match that of the original
configuration, otherwise the modification request is not processed.

The normalization factor is based on instance size within the instance type
(for example, m1.xlarge instances within the m1
instance type). This is only meaningful within the same instance type. Instance
types cannot be modified from one type to another. In the Amazon EC2 console,
this is
measured in units. The following table illustrates the normalization factor that
applies within an instance type.

Instance size

Normalization factor

nano

0.25

micro

0.5

small

1

medium

2

large

4

xlarge

8

2xlarge

16

4xlarge

32

8xlarge

64

9xlarge

72

10xlarge

80

12xlarge

96

16xlarge

128

18xlarge

144

24xlarge

192

32xlarge

256

To calculate the instance size footprint of a Reserved Instance, multiply the
number of instances by the normalization factor. For example, an
t2.medium has a normalization factor of 2 so a reservation for
four t2.medium instances has a footprint of 8 units.

You can allocate your reservations into different instance sizes across the
same instance type as long as the instance size footprint of your reservation
remains the same. For example, you can divide a reservation for one
t2.large (1 x 4) instance into four t2.small (4 x
1) instances, or you can combine a reservation for four t2.small
instances into one t2.large instance. However, you cannot change
your reservation for two t2.small (2 x 1) instances into one
t2.large (1 x 4) instance. This is because the existing
instance size footprint of your current reservation is smaller than the proposed
reservation.

In the following example, you have a reservation with two
t2.micro instances (giving you a footprint of 1) and a
reservation with one t2.small instance (giving you a footprint of
1). You merge both reservations to a single reservation with one
t2.medium instance—the combined instance size footprint
of the two original reservations equals the footprint of the modified
reservation.

You can also modify a reservation to divide it into two or more reservations. In the
following example, you have a reservation with a t2.medium instance.
You divide the reservation into a reservation with two t2.nano
instances and a reservation with three t2.micro instances.

Submitting Modification Requests

You can modify your Reserved Instances using the Amazon EC2 console, the Amazon EC2
API, or a command
line tool.

Amazon EC2 Console

Before you modify your Reserved Instances, ensure that you have read the
applicable restrictions. If you
are modifying instance size, ensure that you've calculated the total instance size
footprint of the reservations that you want to modify and ensure that
it matches the total instance size footprint of your target
configurations.

On the Reserved Instances page, select one or
more Reserved Instances to modify, and choose Modify Reserved
Instances.

Note

If your Reserved Instances are not in the active state or cannot
be modified, Modify Reserved Instances is
disabled.

The first entry in the modification table displays attributes of
selected Reserved Instances, and at least one target configuration
beneath it. The Units column displays the total
instance size footprint. Choose Add for each new
configuration to add. Modify the attributes as needed for each
configuration, and choose Continue when you're
done:

Scope: Choose whether the Reserved Instance applies to an Availability Zone or
to the whole Region.

The state returned shows your request as processing,
fulfilled, or failed.

Troubleshooting Modification
Requests

If the target configuration settings that you requested were unique, you receive a
message that your request is being processed. At this point, Amazon EC2 has only
determined that the parameters of your modification request are valid. Your
modification request can still fail during processing due to unavailable
capacity.

In some situations, you might get a message indicating incomplete or failed modification
requests instead of a confirmation. Use the information in such messages as a
starting point for resubmitting another modification request. Ensure that you
have
read the applicable restrictions
before submitting the request.

Not all selected Reserved Instances can be processed for modification

Amazon EC2 identifies and lists the Reserved Instances that cannot be modified. If
you receive
a message like this, go to the Reserved Instances page in
the Amazon EC2 console and check the information for the Reserved Instances.

Error in processing your modification request

You submitted one or more Reserved Instances for modification and none of your
requests can be processed. Depending on the number of reservations you are
modifying, you can get different versions of the message.

Amazon EC2 displays the reasons why your request cannot be processed. For example,
you
might have specified the same target configuration—a combination of
Availability Zone and platform—for one or more subsets of the Reserved Instances
you are modifying. Try submitting the modification requests again, but
ensure that the instance details of the reservations match, and that the target
configurations for all subsets being modified are unique.

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